Electrodeposition of metals



. contained brighteners.

Patented Nov. 20, 1945 ELECTRODEPOSITION F METALS Henry Brown, Kansas City, Mo., assignor to The Udylite Corporation, Detroit, Mich, a corporation of Delaware No Drawing. Application February 21, 1941, Serial No. 379,950

17 Claims.

My invention relates to improvements in the electrodeposltlon of metals. It is particularly concerned with the utilization of certain addition agents, for the purposes hereinafter stated, in aqueous acidic electro-platlng baths.

I have discovered that certain substances, hereinafter described in detail, when added to electroplating baths, particularly aqueous acidic electroplating baths such as used for the electrodeposition of nickel, cobalt, iron, zinc, cadmium, copper, antimony, various alloys containing the aforementioned and other metals, and the like, are remarkably eflective in the prevention of the formation of pits in the electro-deposlted coatings, said pits normally being caused by the, adherence of gas bubbles during the electrodeposltion of the coating. I have found, further, that this result is accomplished despite the fact that very low concentrations of the addition substances are employed and, still further, that these results are accomplished without causing any significantly appreciable interference with the desired appearance, structure and character of the plate.

I have also discovered that the addition agents are highly effective independently of whether various organic or inorganic so-called brightening agents are also present in the electrolyte bath. Various addition agents have heretofore been suggested for reducing or eliminating pitting in electrodeposition operations but, at least in most cases, and apart from other deficiencies which they possess, they have proven to be wholly unsatisfactory where the electro-deposition bath Thus, for example, in baths employed for the electrodeposition of bright nickel, where the brightening agent comprises an aryl sulphonic acid, for example, naphthalene 1,5 disulphonic acid, sodium salt, or sulphonamides tlcularly those wherein the brlghtener is in the Patent No. 2,191,813, issued February 27, 1940, various suggested anti-pitting agents have proven entirely unsatisfactory. The use of the addition agents in bright plating baths represents but one aspect of my present invention although, to be sure, a highly important one.

The addition agents which I have found to be unusually satisfactory, in accordance with my present invention, can be used in sufliclently low concentrations so as to reduce substantially, or eliminate entirely, pitting of the deposits and, at the same time, they do not interfere to any significantly appreciable extent with the particular cathodic process involved such as reduction of inorganic or organic substances taking place in the process of electrodepositing the coating. This is highly important where the deposited metal is desired not only free from pits but also of maximum ductility and purity and freedom from such inclusions as sulphur, carbon and colloids. It is also of considerable importance in those cases involving bright plating baths, particularly aqueous acid lating baths for the electroplating of nickel, which baths contain brighteners such as those mentioned hereinabove, parform of a soluble compound containing the radical SO2.N=. As I have pointed out hereinabove, the brightness or brilliance or high luster of the deposits is not adversely affected where the addition agents, to which my present invention relates, are employed.

The novel and highly useful addition agents which accomplish the functions set out hereinabove are, in general, aliphatic sulpho-monocarboxylic acid esters of aliphatic alcohols containing from 8 to 18 carbon atoms, the sulphocarboxylic acid radical containing from 2 to 4 carbon atoms. Illustrative addition agents whose or sulphonimides such as are disclosed in my use {9115 within the scope of my present invention are, for example, sulpho-acetates of octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, ricinoleyl alcohol, palmitoleyl alcohol, or

aseaiss tion at least to suchan extent as to fall within the general range as set out hereinabove. In general, the solubility of the addition agents in the electrolyte solutions decreases with the increase or carbon atoms in the alcohol chain of the addition mixtures of such alcohols. Oi! particular utility 5 agents and, therefore, lower concentrations of are the sulpho-acetates of coconut oil mixed such addition agents may be used. Conversely, fatty alcohols containing predominantly lauryl higher concentrations. generally speaking, of those alcohol or special fractions derived from 0000- addition agents should be used where the number nut oil mixed fatty alcohols which are particu- 1U oi! carbon atoms in the alcohol chain is around larly high in their lauryl alcohol content. The 8 or 10 carbon atoms. The addition agents which aliphatic straight chain alcohols are particularly are preferably employed are those derived from desired although, in certain cases, branched chain alcohols containing from 10 to 16 carbon atoms alcohol sulphoacetates may be used such as those and of particular utility are those prepared from derived from 2-n-buty1 octanol-1,2-butyl tetraalcohols containing predominantly 12 to 14 cardecanol-l, and the like, although the results obbon atoms, the lauryl alcohol derivatives bein tained are not so satisfactory. Instead of sulespecially useful. p o ce tes, sulphopropionates. sulp tym s. Table I lists several addition agents which may and, in general, esters of aliphatic sulpho-rnonobe employed in accordance with my invention and I carboxylic aci P r i y p -fa y acids. in the concentrations which are, in general, precontaining from 2 to 4 carbon atoms with aliferred:

Table l Conc., Anion Cation gram liter CHg-(CHflr-CHg-O-b-CEh-B 0r H Na or metal oi bath being used.. 0. 2-0. 5

(Decyl snlphoacetate) I cn,- cn,),r-cnr-0-c-cm-s Or' .---.do 0.1-0.5

(Lauryl sulphoacetete) CHr-(CHflu-CHr-O-C-CHr-B Or .do 0.1-0.5

(Myristyl sulphoacetate) cnrcnot-cnt -o-c-cm-s 0.- .....do dos-0.5

i 11 i al in lsul 11 a... assesses? P cHr-(cB,m-cn,-0-( :-(cH|),-s Or .....do 0.1-0.5

0 (L uryl suiphopropionate) CHr-(CHflu-CHr-O-(i(CHs)s-S Or ....do 0. 05-0. 5

(Myristyl sulphoproplonste) cnr-(cn,).-cm-0-o-(cm),-s Or ....do 0.05-0.5

(Higher fatty coho! sulphopropionates) where n= -l0 (or mixtures) phatic alcohols containing from 8 to 18 carbon atoms, such as those mentioned hereinabove, may be employed. The sulphoacetates or the like are utilized preferably in the form of their free acids or their alkali metal salts Or in the form of a salt of the metal to be electrodeposited. In most cases, it is preferable to utilize the sodium salt.

The addition agents are employed in concentrations of the general order of about 0.05 to about 0.5 gram per liter of electrolyte solution, from about 0.1 to about 0.3 gram per liter of electrolyte solution being most satisfactory in the usual case. More addition agent may be utilized but it is. in general, uneconomic to do soand fully satisfac tory results are obtained in practically all cases with the preferred range set out hereinabove.

It will be understood that the addition agents utilized should be soluble'in the electroly i? soluor otherwise decomposed or modified to an extent sufllcient to interfere with their functioning. In general, the addition agents are particularly eiTective in aqueous acidic electroplating bath wherein the pH of the bath is of the order of about 2 to about 6.

Table II In each bath 0.1-0.5 gram/liter or 0.01-0.07

oz./gal. or

CnHu-O-Ji-C Hr-SOrNa Cone, 00110., Nickel (white) oz. I881. Nickel (white) oL/gaL N1BO4.6-7H3O I 30-40 NiClaGHzO 30-40 NiClmEhO 8 H1130; 5 H33 5 Temp. 70-l50 F pH-4.0-5.5 Cathode C. D. 5-150 ampJsq. it. amp/it.

Nickel (bright) Cobalt ozJgal. oz./gal.

NlSO4.6-7Hz0 30-40 COSQiJHrO 30-40 NlChfiHeO 8 COCh.6H:O 8 HgBO 3130: 5 Cam-501N111 0. 3 (NH4)2SO4 0. 2 ZnSOaJHzO 0. 1 Q. Temp. 100-160 F Temp. 70l20 F iH iiJS-fij pH=3.5-5.5 athode C. D. -75 Cathode C. D. -200 amp/it. amp/it.

Nickel-cobalt 00:10., 71110 00110., (bright) oz./gal. oz./gal.

N1SO4.6-7H:O 32 ZnSO .7H2O. 30-40 COSO4.7H:O 8 Zn(C2Ha02)z-- 4 N1C1:.6H:O 6 A12(sO4)a 2 H3130; 5 HCH 0. l5 Temp. loo-160 F Temp. lilo-150 F. pH=-4.0-5.5 pH=-4.05.5 Cathode C. D. 5-100 Cathode C. D. 10-50 amp/ft. amp/ft.

Conc., Conc., Iron oz./gal. copper oz./gal.

FeCl (11150461120 30-40 CaClzfiHgO C CzHaOz 4 Temp. 100-150" F... Temp. 70-150 F pH-3.5-5.0. pH=-3.05.0 Cathode C.D. 10-100 Cathode C. I). 10-50 amp/it. amp/ft.

While, in the examples listed hereinabove in Table Ii, I have disclosed the use of the sodium salt of lauryi sulphoacetate as the addition agent, it will be understood that others of the addition agents which I have disclosed may be substituted therefor without in any manner departing from the spirit and teachings of my invention.

It will be understood that, from time to time. more addition agent should be added to replenish that which is lost by drag-out" or which may possibly be changed, in some manner or other, during the electrodeposition process.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. In a process of electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited and a minor proportion of a sulpho-fatty acid ester of an aliphatic monohydric alcohol containing from 8 to 18 carbon atoms, said sulpho-fatty acid containing from 2m 4 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

2. In a process for electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited and a minor proportion of a soluble sulpho-fatty acid ester of a mixture of alcohols containing predominantly i'rom 12 to 14 carbon atoms, the sillpho-fatty acid radical containing from 2 to 4 carbon atoms. the metal to be'deposited being selected from the group consisting of nickel, cobalt, iron,'

zinc, cadmium, copper, and antimony.

3. In a process for electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of asalt of the metal to be deposited and a minor proportion of a sulpho-acetate of a mixture of monohydric alcohols containing predominantly 12 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony. 1 Y

4. In a process of electrodepositing nickel, the step which comprises electrolyzing an aqueous acid nickel solution containing a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also containing a minor proportion of lauryl sulpho-acetate.

5. In a process of electrodepositing metals, the

0.5 gram per liter of a sulpho-acetate of an ali-' phatic straight chain monohydric alcohol containing from 12 to 14 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

'7. In a process oi electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited, said solution containing from about 0.1 to about 0.5 gram per liter of a sulpho-acetate of an allphatic monohydric alcohol containing predominantly 12 carbon atoms, the metal to be deposited being selected from the group consisting oi nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

8. A bath for the electrodeposition of metals comprising an aqueous acid solution of a compound oi a metal to be deposited by electrolysis and from about 0.1 to about 0.5.gram per liter of a soluble, aliphatic sulpho-mono-carboxylic acid ester of an aliphatic monohydric alcohol containing from 12 to 14 carbon atoms, the sulpho-carboxylic acid radical containing from 2 to 4 carbon atoms. the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium. copper, and antimony.

9. A bath for the electrodeposition of metals comprising an aqueous acid solution of a compound of a metal to be deposited by electrolysis and a minor proportion of a suloho-acetate of an aliphatic monohydric alcohol containing from 12 to 14 carbon atoms. the metal to be deposited being selected from the group consisting of nickel, cobalt, iron. zinc, cadmium. copper. and antimony.

10. A bath for the electrodcposition of nickel comprising an aqueous acid solution of a material selected from the group consisting oi. nickel sulphate, nickel chloride, and mixtures thereof,- and a minor proportion of a sulpho-iatty acid ester of an aliphatic straight chain alcohol containing from 12 to 14 carbon atoms, the sulphoiatty acid radical containing from 2 to 4 carbon atoms.

11. A bath for the electrodeposition of nickel comprising an aqueous acid solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, and from about 0.1 to about 0.5 gram per liter of a sulpho-fatty acid ester of an aliphatic straight chain alcohol containing largely lauryl alcohol, the sulpho-fatty acid radical containing from 2 to 4 carbon atoms.

12. A bath for the electrodeposition of nickel comprising an acid aqueous solution of a material selected from the group consisting oi nickel sulphate, nickel chloride, and mixtures thereof, and a minor proportion of a sulphoacetate of an aliphatic straight chain monohydric alcohol containing from 12 to 14 carbon atoms.

13. In a process of electrodepositing nickel to Q obtain a bright or lustrous deposit, the step which comprises electrolyzing an aqueous acid nickel solution containing a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also containing minor proportions of an aryl sulphonic acid brightener and a soluble sulpho-fatty acid ester of an alcohol containing from 8 to 18 carbon atoms, the sulpho-fatty acid radical containing from 2 to 4 carbon atoms.

14. In a process of electrodepositing nickel to obtain a bright or lustrous deposit, the step which comprises electrolyzing an aqueous acid nickel solution containing a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also containing minor proportions of an aryl sulphonic acid brightener and lauryl sulphoacetate.

15. In a process of electrodepositing nickel to obtain a bright or lustrous deposit, the step which comprises electrolyzing an aqueous acid nickel solution containing a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also containing minor proportions of lauryl sulphoacetate and a brightener in the form of a compound soluble in the solution and containing the group -SO2.N==.

16. A bath for the electrodeposition of nickel in the form of a bright or lustrous deposit, comprising an aqueous acid solution of a material selected from the group consisting of nickelsulphate, nickel chloride, and mixtures thereof, and

.minor proportions of a soluble sulpho-Iatty acid ester of an aliphatic straight chain alcohol containing from 8 to 18 carbon atoms, the sulphofatty acid radical containing from 2 to 4 carbon atoms.

17. A bath for the electrodeposition of nickel in the form of a bright or lustrous deposit, comprising an aqueous acid solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, and minor proportions of a sulphoacetate of an allphatic straight chain monohydric alcohol containing from 12 to 14 carbon atoms, and a brightener, said brightener comprising a compound soluble in the solution and containing the group -SO2.N=.

HENRY BROWN. 

